Air bag module with vent cover

ABSTRACT

A vehicle occupant protection apparatus ( 10 ) comprises an inflatable device ( 12 ) for helping to protect a vehicle occupant, and an inflator ( 14 ). The inflator ( 14 ) has a cylindrical configuration and a plurality of inflation fluid outlets ( 24 ). A vent member ( 30 ) connected with the inflator ( 14 ) has an annular vent wall ( 60 ) having at least one vent opening ( 62 ). A vent cover ( 100 ) has a closed condition clamped on the vent wall ( 60 ) and covering the vent opening ( 62 ), and an open condition removed at least partially from the vent wall and enabling fluid flow through the vent opening. An actuatable device ( 130 ) on the vent cover ( 100 ) has an unactuated condition maintaining the vent cover in the closed condition, and an actuated condition releasing the vent cover for movement to the open condition to vent inflation fluid from the apparatus ( 10 ).

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a vehicle occupant protection apparatus including an inflatable vehicle occupant protection device, such as an air bag. In particular, the present invention relates to an air bag module in which inflation fluid is selectively vented from the module, and to a cover for a vent in such a module.

DESCRIPTION OF RELATED ART

[0002] It is known to inflate an air bag to help protect a vehicle occupant in the event of sudden deceleration such as occurs in a vehicle collision. The air bag is stored in a deflated condition, together with an inflator, in a housing adjacent to the vehicle seat in which the occupant sits. The inflator, when actuated, provides a large volume of inflation fluid to inflate the air bag into a position to help protect the vehicle occupant.

[0003] Under normal circumstances, substantially all of the inflation fluid from the inflator is directed into the air bag to inflate the air bag. In some circumstances, however, it may be desirable to control or limit the amount of inflation fluid directed into the air bag. For example, if the vehicle occupant is smaller than a predetermined size or is closer to the vehicle instrument panel than a predetermined distance, then it may be desirable to reduce the speed and force with which the air bag inflates. It is known to vent inflation fluid from the housing of an air bag module in such circumstances, so that less inflation fluid is directed into the air bag. This venting may be accomplished by moving a member, such as a door panel, that normally covers a vent opening in the module.

SUMMARY OF THE INVENTION

[0004] The present invention is a vehicle occupant protection apparatus comprising an inflatable vehicle occupant protection device for, when inflated, helping to protect the vehicle occupant. An inflator provides inflation fluid for inflating the protection device. The inflator has a generally cylindrical configuration and a plurality of inflation fluid outlets. A vent member connected with the inflator has an annular vent wall having at least one vent opening. The apparatus includes a vent cover having a closed condition clamped on the vent wall and covering the vent opening. The vent cover has an open condition removed at least partially from the vent wall and enabling fluid flow through the vent opening to vent inflation fluid from the apparatus. An actuatable device on the vent cover has an unactuated condition maintaining the vent cover in the closed condition on the vent wall. The actuatable device has an actuated condition releasing the vent cover for movement from the closed condition to the open condition to enable fluid flow through the vent opening to vent inflation fluid from the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The foregoing and other features of the invention will become apparent to one skilled in the art to which the invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which:

[0006]FIG. 1 is a schematic illustration, partially in section, of a vehicle occupant protection apparatus constructed in accordance with the present invention, including a vent cover shown in a closed condition;

[0007]FIG. 2 is an illustration similar to FIG. 1 showing the vent cover in an open condition;

[0008]FIG. 3 is a perspective view of the vent cover of FIG. 1;

[0009]FIG. 4 is a bottom plan view of the vent cover of FIG. 1;

[0010]FIG. 5 is a side elevational view of the vent cover of FIG. 1, including an actuatable fastener shown in an unactuated condition;

[0011]FIG. 6 is a view similar to FIG. 5 showing the actuatable fastener in an actuated condition; and

[0012]FIG. 7 is an exploded perspective view of the apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention relates to a vehicle occupant protection apparatus including an inflatable vehicle occupant protection device, such as an air bag. In particular, the present invention relates to an air bag module in which inflation fluid is selectively vented from the module in order to control the pressure, speed and force of deployment of the inflating air bag. As representative of the present invention, FIGS. 1-7 illustrate a vehicle occupant protection apparatus 10 constructed in accordance with the invention.

[0014] The apparatus 10 includes an air bag module 11. The module 11 includes an inflatable vehicle occupant protection device 12 of the type commonly known as an air bag. Other occupant protection devices that can be used in accordance with the invention include, for example, inflatable knee bolsters, inflatable headliners, inflatable side curtains, knee bolsters actuatable by air bags, and seat belt pretensioners.

[0015] The module 11 also includes an inflator 14. The inflator 14 comprises a source of inflation fluid for inflating the air bag 12. As known in the art, the inflator 14 may contain an ignitable gas-generating material, which, when ignited, rapidly generates a large volume of gas. The inflator 14 may alternatively contain a stored quantity of pressurized inflation fluid, or a combination of pressurized inflation fluid and ignitable material for heating the inflation fluid.

[0016] The inflator 14 illustrated in the drawings has a cylindrical configuration centered on an axis 16. The inflator 14 could have a configuration other than the cylindrical configuration illustrated in the drawings. The inflator 14 has a main body portion 18 and an annular mounting flange 20. The main body portion 18 includes an annular side wall 22 having a plurality of inflation fluid outlets 24 through which inflation fluid is directed radially outward upon actuation of the inflator 14. The inflator 14 further includes an electrical connector 26 for receiving an electric actuation signal.

[0017] The module 11 also includes a mounting member 30. The mounting member 30 is a structure that supports the other parts of the air bag module 11 on the vehicle, and that assumes the reaction forces of the inflator and the air bag when actuated. In the illustrated embodiment, the mounting member is a reaction plate.

[0018] The reaction plate 30 has a rectangular, planar central portion 32 with a circular central opening 34 for receiving the inflator 14. Four fastener openings 36 extend through the central portion 32 of the reaction plate 30, radially outward of the central opening.

[0019] The reaction plate 30 has two cover support flanges 38 that extend upward from opposite sides of the central portion 32. Two other cover support flanges 40 extend in an opposite direction, from the other two sides of the central portion 32. The reaction plate 30 also includes two module mounting flanges 42 that are secured to the vehicle in a manner not shown, and that support the reaction plate 30 on the vehicle.

[0020] The reaction plate 30 has a vent portion 50. The vent portion 50 has a cylindrical, cage-like configuration and includes a circular upper rim 52 that depends from the central portion 32 of the reaction plate 30, centered on the axis 16. The vent portion 50 also includes a plurality of tabs 54 that extend downward from the upper rim 52 and are interconnected by a lower rim 56.

[0021] The tabs 54 are spaced apart in a circular array centered on the axis 16. The tabs 54 and the rims 52 and 56 together form a perforate, annular vent wall 60 of the reaction plate 30. The vent wall 60 has a vent opening 62 that comprises a plurality of slots 64, which are the spaces between the tabs 54.

[0022] The module 11 includes a retainer 70 that is connected with the air bag 12 and that retains, or secures, the air bag in the apparatus. The retainer 70 has a ring-shaped body portion 72 extending around the main body portion 18 of the inflator 14. The body portion 72 of the retainer 70 has a circular central opening 74.

[0023] The retainer 70 includes four support posts 76, although a different number of support posts, or a different type of structure, could be provided. The support posts 76 extend into the fastener openings 36 in the central portion 32 of the reaction plate 30. Nuts 78 screwed on the support posts 76 secure the retainer 70 to the reaction plate 30.

[0024] The air bag 12 has a main body portion 80, and a mouth portion 82 with a circular inflation fluid opening 84. The mouth portion 82 of the air bag 12 is clamped between the body portion 72 of the retainer 70 and the central portion 32 of the reaction plate 30. As a result, the air bag 12 is secured to the reaction plate 30.

[0025] The retainer 70 also has four clamp legs 86 that depend from the body portion 72. The clamp legs 86 are located at the outer periphery of the central opening 74 of the retainer 70. The clamp legs 86 are in the form of rigid tabs that are spaced apart in a circular array about the axis 16.

[0026] The clamp legs 86 engage the mounting flange 20 of the inflator 14 and press it axially against the lower rim 56 of the vent portion 50 of the reaction plate 30. As a result, the mounting flange 20 of the inflator 14 is clamped between the retainer 70 and the reaction plate 30. The inflator 14 is thus secured in the module 11, with the air bag 12 and the retainer 70, on the reaction plate 30.

[0027] When the inflator 14 is secured on the reaction plate 30, the vent wall 60 of the reaction plate is located radially outward of the side wall 22 of the inflator. An annular plenum chamber 90 is defined radially outward of the inflator side wall 22 and radially inward of the reaction plate vent wall 60. The clamp legs 86 of the retainer 70 extend through the plenum chamber 90.

[0028] The module 11 includes a vent cover 100. The vent cover 100 is a structure that covers the vent opening 62 in the vent wall 60 of the reaction plate 30 when the inflator 14 is unactuated. The vent cover 100 is selectively removable from the reaction plate 30, in a manner described below, to enable venting of inflation fluid from the module 11.

[0029] The vent cover 100 in the illustrated embodiment is formed as a split ring having a planar, ring-shaped bottom wall 102. The bottom wall 102 has an inner peripheral portion that defines a circular central opening 106 in the bottom wall. The bottom wall also has an outer peripheral portion 108 (FIG. 4).

[0030] A cylindrical side wall 110 of the vent cover 100 extends upward from the outer peripheral portion 108 of the bottom wall 102. The side wall 110 has an inner diameter approximately equal to the outer diameter of the vent wall 60 of the reaction plate 30.

[0031] The side wall 110 of the vent cover 100 has first and second end portions 112 and 114. A first radially extending mounting flange 116 is disposed on the first end portion 112 of the side wall 110 and has a fastener opening 118. A second radially extending mounting flange 120 is disposed on the second end portion 114 of the side wall 110 and has a fastener opening 122. A nut 124 is welded or otherwise attached on the second radially extending mounting flange 120 at the fastener opening 122.

[0032] The first and second mounting flanges 116 and 120 extend parallel to each other and overlie each other when the vent cover 100 is in the closed condition shown in FIGS. 1-5. The fastener opening 122 in the second mounting flange 120 overlies the fastener opening 118 in the first mounting flange 116.

[0033] When the vent cover 100 is assembled with the inflator 14 and the reaction plate 30, the main body portion 18 of the inflator extends through the central opening 106 in the bottom wall 102 of the vent cover. The side wall 110 of the vent cover 100 overlies the vent wall 60 of the reaction plate 30, and covers the slots 64 of the vent opening 62 in the reaction plate.

[0034] The dimensions of the vent cover 100 are selected so that the vent cover is securely clamped on the vent wall 60 of the reaction plate 30 when the first and second mounting flanges 116 and 120 are brought together. An actuatable fastener 130, in the form of an explosive bolt, extends through the fastener openings 118 and 122 in the mounting flanges 116 and 120, respectively, and is screwed into the weld nut 124. The fastener 130 clamps together the first and second mounting flanges 116 and 120. As a result, the vent cover 100 is clamped on the vent wall 60 of the reaction plate 30. The side wall 110 of the vent cover 100 blocks fluid flow through the slots 64 of the vent opening 62.

[0035] In the illustrated embodiment, the actuatable fastener 130 is a an explosive bolt that is electrically actuatable by an electric current over lead wires 132. The actuatable fastener 130 may take different forms. The actuatable fastener 130 may alternatively be an explosive rivet, for example.

[0036] The inflator 14, the air bag 12, and the retainer 70 are, in the illustrated embodiment, enclosed in a cover 140. The cover 140 is preferably made from plastic and includes a side wall 142 and a top wall 144. The top wall 144 has a predetermined weakened portion or tear seam 146 (FIG. 1) The cover 140 has two mounting flanges 148 that extend from the side wall 142 and two mounting flanges 150 that extend from the top wall 144. Cover retainers 152 and rivets 154 secure the mounting flanges 148 to the reaction plate flanges 38. Additional rivets 156 secure the mounting flanges 150 of the cover 140 to the reaction plate flanges 40. (The cover 140 could be mounted or attached through other means.) When the cover 140 is thus mounted on the reaction plate 30, the top wall 144 and side wall 142 of the cover, together with the reaction plate 30 and the inflator 14, define a chamber 158 (FIG. 1) in the apparatus 10. The inflation fluid outlets 24 of the inflator 14 are located in the chamber 158.

[0037] The apparatus 10 includes vehicle electric circuitry indicated schematically at 160 (FIG. 2). The vehicle electric circuitry 160 controls the operation of the inflator 14 and the actuatable fastener 130. The vehicle electric circuitry 160 includes a power source 162, which is preferably the vehicle battery and/or a capacitor, and a normally open switch 164. The switch 164 is part of a collision sensor 166, which senses a condition indicating the occurrence of a vehicle collision. The collision-indicating condition may comprise, for example, sudden vehicle deceleration caused by a collision. The vehicle electric circuitry 160 further includes a controller, or control module, 170 for controlling the operation of the vehicle electric circuitry, and a sensor assembly 172.

[0038] The sensor assembly 172 includes one or more sensors that generate one or more control signals useful in determining whether to inflate the air bag 12 with maximum speed and force when a vehicle collision is sensed. For example, the sensor assembly 172 may include an occupant position sensor that generates a control signal indicative of the position of a vehicle occupant in the interior of a vehicle. The sensor assembly 172 may also include a buckle switch for generating a control signal indicative of a buckled or unbuckled condition of a seat buckle assembly of the vehicle. The sensor assembly 172 may also include a sensor that senses the presence of a rearward-facing child seat, a weight sensor, a belt tension sensor, an occupant size sensor, a module temperature sensor, or a crash severity sensor.

[0039] If a collision-indicating condition sensed by the collision sensor 166 is above a predetermined threshold, it indicates the occurrence of a collision for which inflation of the air bag 12 is desired to help protect the occupant of the vehicle. The switch 164 in the collision sensor 166 closes and the control module 170 transmits an actuation signal to the inflator 14 over lead wires 174. When the inflator 14 is actuated, it emits a large volume of inflation fluid from the inflation fluid outlets 24, into the plenum chamber 90.

[0040] The inflation fluid flows from the plenum chamber 90, through the retainer 70, and into the mouth portion 82 of the air bag 12. The inflation fluid begins to inflate the air bag 12, which moves rapidly and forcefully outward against the top wall 144 of the cover 140. The cover 140 opens and the air bag 12 inflates into a position to help protect the vehicle occupant.

[0041] Upon such an occurrence of a condition requiring actuation of the inflator 14, the control module 170 receives the control signals from the sensor assembly 172. The control module 170 determines, on the basis of those signals, whether it is desirable to actuate the fastener 130. This determination, as well as the actuating of the fastener 130 itself, can be made prior to actuation of the inflator 14, or at the same time as actuation of the inflator, or after actuation of the inflator.

[0042] The control signals from the sensor assembly 172 may indicate a condition in which it is desirable that the air bag 12 be inflated with maximum force and speed. If the control module 170 receives signals indicating such a condition, the control module determines that the actuatable fastener 130 should remain in the unactuated condition. The fastener 130 is not energized by the control module 170, and maintains the flanges 116 and 120 of the vent cover 100 clamped against each other. The vent cover 100 remains clamped on the vent portion 50 of the reaction plate 30, covering the slots 64 of the vent opening 62. As a result, all the inflation fluid from the inflator 14 is directed from the plenum chamber 90 into the inflation fluid opening 84 of the air bag 12, as indicated by the arrows 180 (FIG. 1), and the air bag inflates with maximum speed and force.

[0043] On the other hand, one or more of the control signals from the sensor mechanism 172 may indicate a condition in which it is desirable not to inflate the air bag 12 with maximum speed and force. If the control module 100 receives a signal indicative of such a condition, the control module determines that the fastener 130 should be actuated. A control signal is transmitted from the control module 170, through the lead wires 132, to the fastener 130. The fastener 130 is electrically energized and moves from the unactuated position shown in FIG. 1 to a second, or actuated, position shown in FIG. 2.

[0044] The fastener 130, which in the illustrated embodiment is an explosive bolt, fractures. As a result, the fastener 130 no longer secures the first mounting flange 116 of the vent cover 100 to the second mounting flange 120 of the vent cover. The vent cover 100 is free to spring apart circumferentially and move away from the vent portion 60 of the reaction plate 30, under the influence of the explosive force of the bolt 130 and of gravity.

[0045] The vent cover 100 moves from the installed or closed condition shown in FIG. 1 to an open condition off the vent wall 60 of the reaction plate 30, as shown in FIG. 2. The movement of the vent cover 100 enables at least some inflation fluid to be vented through the slots 64 of the vent opening 62, as indicated by the arrows 182 (FIG. 2). The vent cover 100 may come to rest on the steering wheel hub (not shown).

[0046] The inflation fluid that flows out of the chamber 90 through the vent opening 62 does not flow into the air bag 12 to inflate the air bag. In addition, some inflation fluid flows out of the air bag 12 through the vent opening 62, as indicated by the arrows 183. As a result, the amount of inflation fluid flowing into the air bag 12, or the pressure of the inflation fluid, is reduced as compared to the amount or pressure of inflation fluid flowing into the air bag when the fastener 130 remains unactuated. This change in the flow of inflation fluid can help to reduce or control the pressure, speed and force of deployment of the air bag 12.

[0047] From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims. 

Having described the invention, we claim:
 1. A vehicle occupant protection apparatus comprising: an inflatable vehicle occupant protection device for, when inflated, helping to protect the vehicle occupant; an inflator for providing inflation fluid for inflating said protection device, said inflator having a generally cylindrical configuration and having a plurality of inflation fluid outlets; a vent member connected with said inflator and having an annular vent wall having at least one vent opening; a vent cover having a closed condition clamped on said vent wall and covering said vent opening, said vent cover having an open condition removed at least partially from said vent wall and enabling fluid flow through said vent opening to vent inflation fluid from said apparatus; and an actuatable device on said vent cover, said actuatable device having an unactuated condition maintaining said vent cover in the closed condition on said vent wall, said actuatable device having an actuated condition releasing said vent cover for movement from the closed condition to the open condition to enable fluid flow through said vent opening to vent inflation fluid from said apparatus.
 2. An apparatus as set forth in claim 1 wherein said actuatable device comprises an explosive bolt.
 3. An apparatus as set forth in claim 1 wherein said vent cover has a cylindrical configuration.
 4. An apparatus as set forth in claim 1 wherein said vent cover is formed as a split ring and has a cylindrical outer wall.
 5. An apparatus as set forth in claim 4 wherein said outer wall of said vent cover has first and second end portions, a first mounting flange is disposed on said first end portion of said outer wall, and a second mounting flange is disposed on said second end portion of said outer wall.
 6. An apparatus as set forth in claim 5 wherein said first and second mounting flanges extend parallel to each other and overlie each other when said vent cover is in the closed condition to clamp said vent cover on said vent wall, and wherein said actuatable device extends through said first and second mounting flanges.
 7. An apparatus as set forth in claim 1 further comprising a retainer having an annular, radially extending main body portion for clamping said protection device to said vent member, said retainer having a plurality of axially extending, circumferentially spaced clamping legs for clamping said inflator to said vent member at a location radially between said inflation fluid outlets of said inflator and said vent opening; said circumferentially spaced clamping legs of said retainer defining between them a plurality of circumferentially spaced fluid passages that provide fluid communication between said inflation fluid outlets of said inflator and said vent opening in said reaction plate.
 8. An apparatus as set forth in claim 7 wherein said vent member comprises a reaction member for supporting said apparatus on the vehicle.
 9. An apparatus as set forth in claim 1 wherein said vent member comprises a reaction member for supporting said apparatus on the vehicle.
 10. A vehicle occupant protection apparatus comprising: an inflatable vehicle occupant protection device for, when inflated, helping to protect the vehicle occupant; an inflator for providing inflation fluid for inflating said protection device, said inflator having a generally cylindrical configuration centered on an axis and having a plurality of inflation fluid outlets for directing inflation fluid to flow radially outward from said inflator; a reaction plate for supporting said inflator and said protection device on the vehicle, said reaction plate having at least one vent opening disposed radially outward of said inflation fluid outlets of said inflator; a retainer having an annular, radially extending main body portion for clamping said protection device to said reaction plate and having a plurality of axially extending, circumferentially spaced clamping legs for clamping said inflator to said reaction plate at a location radially between said inflation fluid outlets of said inflator and said vent opening of said reaction plate; said circumferentially spaced clamping legs of said retainer defining between them a plurality of circumferentially spaced fluid passages that provide fluid communication between said inflation fluid outlets of said inflator and said vent opening in said reaction plate; a vent cover having a closed condition clamped on said reaction plate and covering said vent opening; and an actuatable device on said vent cover, said actuatable device having an unactuated condition maintaining said vent cover in the closed condition clamped on said reaction plate, said actuatable device having an actuated condition releasing said vent cover for movement from the closed condition to an open condition removed at least partially from said reaction plate and enabling fluid flow through said vent opening to vent inflation fluid from said apparatus.
 11. An apparatus as set forth in claim 10 wherein said reaction plate has a cylindrical vent wall in which said vent opening is formed, said vent cover having a cylindrical portion covering said vent opening in said cylindrical vent wall.
 12. An apparatus as set forth in claim 11 wherein said cylindrical vent wall depends from a planar central portion of said reaction plate. 